Several types of devices which are adapted to detect undesired movement of rotating objects or to detect bearing wear are known in the prior art. For example, U.S. Pat. No. 3,513,375 granted to Sellars discloses a safety stopping device which acts to close an electric circuit and thereby ground a motor to stop the motor, when the device detects eccentric shaft motion. When a shaft of the Sellars patent rotates eccentrically, it contacts and moves a sensor contact element, which allows a dog to disengage from the sensor contact element and trip a leaf spring, which urges the contact element into electrical contact with the shaft to ground the motor. The device of the Sellars patent has the disadvantage, however, that it is relatively complicated and thus may be relatively difficult and expensive to manufacture and repair.
U.S. Pat. No. 3,897,116 granted to Carpenter discloses a bearing wear detector which includes a pin which has an electrically-insulating coating thereon and which is mounted with one end inside a rotatable shaft. The rotatable shaft carries a metallic disc therein which rotates with the shaft in close non-contacting relationship with the pin, and, when the shaft rotates off-line due to bearing wear, the disc wears through the coating to make electrical contact with the pin and thereby complete a circuit which sets off an alarm system. The Carpenter device has the disadvantage, among others, that the coating on the pin is worn through each time the shaft rotates off-line, and thus the pin must be removed and replaced each time after the alarm system is activated. The Carpenter device is thus relatively costly and time-consuming to maintain on a continuous basis.
U.S. Pat. No. 893,865 granted to Ormiston et al. discloses a telltale apparatus which includes a pair of ebonite castings located below a shaft which are movable relative to each other and which are spring biased apart, and pairs of hollow contact points located on each of the ebonite castings, respectively. When bearings holding the shaft wear down to a certain point, the shaft will rest on the upper one of the ebonite castings, and will force it downward so that the pairs of contact points will meet and thereby close a circuit to ring an alarm bell. A disadvantage of the Ormiston et al. device is that a relatively large amount of bearing wear is needed before the circuit in the Ormiston et al. device will close, and the Ormiston et al. device is thus relatively undesirable for use in detecting small amounts of undesired eccentric rotation of a shaft which may be caused by bearing wear. Also, since the Ormiston et al. device is located within the shaft's housing, the device is difficult to install, and, once the device is installed, it is difficult to adjust the level of bearing wear which the device will detect.
In view of the above, it is an object of the present invention to provide an improved detecting device which is readily capable of detecting undesired movement of a shaft relative to a bearing.
A further object of the present invention is to provide a detecting device which is effective to detect relatively small amounts of undesired movement of a shaft relative to a bearing.
A still further object of the present invention is to provide a detecting device which operates to greatly reduce the need for costly repairs to an apparatus which includes a rotating shaft.
Yet another object of the present invention is to provide a detecting device which is relatively inexpensive and simple to maintain on a continuous basis.
Another of the objects of the present invention is to provide a detecting device which includes a redundancy of detecting switches so that the device will still operate effectively even if one detecting switch fails.
It is a further object of the present invention to provide a detecting device which is relatively easy and inexpensive to manufacture and repair when needed.
Additionally, it is a further object of the present invention to provide a detecting device which needs repair relatively rarely.
The present invention also has the object to provide a detecting device which may be installed easily on a rotatable shaft.
It is a further object of the present invention to provide a detecting device which can operate an alarm, a recording device, and/or a power disconnection circuit.
Another object of the present invention is to provide a detecting device in which the amount of undesired movement which will be detected is readily adjustable.
The above objects, as well as other objects not specifically enumerated, are accomplished by a detecting device for detecting undesired movement of a shaft relative to a bearing in accordance with the present invention. The detecting device for detecting undesired movement of a shaft relative to a bearing in accordance with the present invention includes housing means for the shaft and bearing, detecting means, switch means, and mounting means for mounting the detecting means to the housing means such that the detecting means contacts the shaft and pivots when a point on a longitudinal axis of the shaft moves off of a central axis of the bearing, wherein the pivoting of the detecting means actuates the switch means so that the undesired movement of the shaft relative to the bearing is detected.
The objects of the present invention are also accomplished by a detecting device for detecting undesired movement of a shaft relative to a bearing, which includes a housing, a rod pivotally mounted to the housing, wherein the rod has a first end thereof for contacting the shaft, and at least one detecting switch mounted on the housing adjacent the rod, wherein the rod is pivotable when a point on a longitudinal axis of the shaft moves from a central axis of the bearing, and wherein the pivoting of the rod actuates the detecting switch.
The objects of the present invention are further accomplished by a detecting device for detecting undesired movement of a shaft relative to a bearing, which includes a housing, a rod having a first end pivotally attached to the shaft and having a second end, wherein the rod is pivotally attached within the housing intermediate the first and second ends, and a pair of switches located a distance from the first end of the rod such that the pivotal attachment is intermediate the first end and the switches, wherein the rod pivots within the housing when a point on the longitudinal axis of the shaft moves from a central axis of the bearing, and wherein the rod closes at least one of the switches during the pivoting so that the undesired movement of the shaft relative to the bearing is detected.